Project Summary The neural crest and cranial placodes are transient embryonic structures derived from adjacent ectodermal domains at the neural plate border, which undergo extensive migration and/or morphogenetic changes and contribute to an extraordinary array of cell types essential for human form and function. Their evolution and elaboration are thought to have been critical for the evolution and diversification of vertebrates. Neural crest cells give rise to all peripheral glia, all peripheral autonomic and enteric neurons and most peripheral somatosensory neurons, as well as adrenal chromaffin cells, pigment cells, craniofacial cartilages and bones, the dentine-producing odontoblasts of teeth, the aorticopulmonary septum of the heart, and the ciliary muscles and corneal endothelium of the eye. Neural crest defects underlie, for example, many congenital craniofacial anomalies and heart defects, and enteric nervous system disorders such as Hirschsprung disease. The reactivation of developmental processes such as epithelial-mesenchymal transition is important for cancer progression; indeed, some of the most aggressive cancers, including melanoma and neuroblastoma, arise from neural crest-derived cells. Placodes form the paired peripheral sense organs (the olfactory epithelia, the inner ears and the lateral line system of fishes and amphibians, including their afferent neurons, plus the eye lenses), as well as afferent neurons for taste-buds and the visceral organs, hypothalamic gonadotropin-releasing hormone neurons (required for fertility, since they trigger puberty) and the endocrine anterior pituitary gland, essential for homeostasis. The clinical significance of cranial placodes includes congenital deafness, congenital hypopituitarism, and the combined anosmia and infertility of Kallmann syndrome, while the fish lateral line is a model for hair cell development, regeneration, and screening for drugs that protect against ototoxic drugs. Recent advances in generating both neural crest and placode derivatives from human stem cells are highly promising avenues for future approaches to regenerative medicine. The Neural Crest and Cranial Placodes Gordon Research Conference and the associated trainee-organized Gordon Research Seminar aim to bring together diverse scientists from across the spectrum of this broad research field, using a variety of model systems, in order to exchange unpublished data and novel approaches, form new collaborations, and mentor junior scientists, in an informal, supportive environment. Sessions are designed to promote interaction between scientists focused on basic mechanisms and those with a direct clinical focus: they run the gamut from early stages in neural crest and placode formation, cell potential and fate choice, tissue interactions, morphogenesis and organogenesis, migration and patterning, to birth defects and disease, stem cells and regenerative medicine.